1. Field of the Invention
The present invention relates to a sleeve type casing for receiving a recording medium such as a tape cassette or a floppy disk, which is prepared by punching out a sheet material with ruled lines for bending.
2. Discussion of Background
Heretofore, tape cassettes and floppy disks in use of audio or video have been protected by putting them in casings made of a material such as a synthetic material, paper or the like. When dust is deposited on the surface of a recording medium such as a magnetic tape or a magnetic disk, a flaw is resulted on the surface, whereby recorded information is lost or there causes erroneous recording or erroneous display. Accordingly, it is necessary to pay attention to the construction of the casing in order to protect a tape cassette or a floppy disk received therein when it is transported or preserved, and to provide easiness for putting-in and drawing-out the tape cassette or the floppy disk.
Description will be made as to form a casing for receiving a video tape cassette, for instance, a sleeve type casing for video tape cassette. A plastic sheet having a large surface area on which printing is formed is punched out to form a large number of blanks. Then, each of the blanks is subjected to line-forming operations by hot pressing so that ruled lines for bending are formed. Then, a blank 10 as shown in FIG. 7 can be obtained. It is possible to form the ruled line for bending in each of the blanks when the blanks are punched out from a plastic sheet.
FIG. 7 shows a blank 10 for a sleeve type casing in a developed form. The blank comprises a front surface area 12, a bottom surface area 14, a rear surface area 16, front side flaps 18 (18a, 18b), back side flaps 20 (20a, 20b) and ear flaps 22 (22a, 22b). The blank is further provided with a ruled line 24 at the border between the front surface area 12 and the bottom surface area 14, ruled lines 26 (26a, 26b) at the borders between the front surface area 12 and the rear side flaps 20, a ruled line 28 at the border between the bottom surface area 14 and the rear surface area 16, ruled lines 30 (30a, 30b) at the borders between the bottom surface area 14 and the ear flaps 22, and ruled lines 32 (32a, 32b) at the borders between the rear surface area 16 and the front side flaps 18.
The blanks having the above-mentioned structure are successively put into a box machine. Each of the blanks 10 are bent so that the flaps 18, 20, 22 which are formed at opposing portions of the blank are respectively overlapped and bonded, whereby left and right side portions 34, 36 are formed in a sleeve type casing 38 for a video tape cassette as shown in FIG. 8. In FIG. 8, numeral 40 (40a, 40b) designates notched portions which provide easiness to draw out the tape cassette by fingers from the opening 42 of the casing 38.
Since the conventional sleeve type casing 38 has the opening 42, dust is apt to enter in the casing and the tape cassette received therein is easily out. Accordingly, the casing 38 is wrapped with a packaging film to close the opening 42 for transportation and preservation. The packaging film has to be broken when the tape cassette is used. Then, there arises again problems that dust enters into the casing through the opening 42 and the tape cassette easily drops.